Object Oriented Dilemma
Posted on 2004-04-24
I have a flowchart drawing tool that enables me to draw boxes and the capability to assign an object to each box. In my program, I have a number of functions and subs that perform tasks. And I enable the user to assign these functions to the box.
As an example, in our program we have three functions: copyfile, movefile, and deletefile. Copyfile and movefile have parameters of SourcePathAndName and DestPathAndName, while deletefile only requires a parameter of SourcePathAndName. Each of functions returns a boolean result of success or failure of the copy, move, or delete.
The question is, what is the smart way to design this program so that as I add additional functions (and there will be many more) I can smartly manage the hooks to my "presentation layer" and "execution layer" with the minimum number of steps.
Currently I declare a string array of functions which I load programmatically, replicating the functions I have already created that I want the user to use (in our example, copyfile, movefile, and deletefile). Then at "the other end of the program" where I actually perform the activity (copy, move, or delete the file) I look at the box object and the function assigned to it, do a "select case" based on the assigned function, and call the appropriate function.
My approach works, but whenever a new function (capability) is added, I have to add that function to my "functions array" so my user will be able to see it and assign it to a box. And in my execution routine, I have to add another case statement to call it. It seems like there must be a smarter approach.
I have looked at the programming techniques of reflection and also creating a delegate (to directly execute the function rather than using a series of case statements). Both of these techniques appear promising, but alas I'm not sure if they are applicable to this dilemma.
The best suggestion and sample of how to approach this wins the points. Thank you!